Automotive fuel tanks are typically supplied with one or more vapor venting valves of different type to selectively vent fuel vapor from the interior of the fuel tank. Commonly used valves include "ORVR" (onboard refueling/vapor recovery) control valves and rollover valves. Fuel tank mounted vapor vent valves typically have a hollow valve body which is inserted through an opening formed in the tank such that a lower part of the valve body is located in the tank, and an upper part or cover of the valve body remains outside the tank. In many cases the lower and upper portions of the valve body are formed separately and are connected mechanically or by known methods such as ultrasonic welding, heat staking or overmolding. The lower portion of the valve body is sized to fit through the opening in the fuel tank, while the upper portion of the valve body is wider to keep the valve assembly from falling through the fuel tank opening.
A common method for securing the valve assembly to the tank is to provide a weldable connector portion on the upper valve body made from a weldable material similar to the material of the fuel tank wall. When the valve assembly is inserted through the fuel tank opening, the weldable connector rests on the upper surface of the fuel tank and is welded to the fuel tank wall to secure the valve in place. Examples of valves with weldable connectors are shown in co-owned U.S. Pat. No. 5,404,907,137/587 issued May 11, 1995.
Mechanical connection of the non-weldable and weldable portions of the valve is often preferred, due to its simplicity and low costs. But while the weld between the weldable upper portion of the valve body and the fuel tank wall is highly reliable, the mechanical connection with the lower valve body is often subject to thermal expansion and creep under fuel tank operating conditions, which can loosen the connection between the lower valve body and the upper valve body or cover, destroying the integrity of the mounting arrangement and of seals between the upper and lower portions. The present invention is directed to overcoming this problem.